Delta herpesvirus infection in Erythrocebus patas monkeys - A model for human herpes zoster complications: Experimental studies have indicated that patas monkeys become persistently infected with Delta herpesvirus (DHV). We are investigating how to activate this persistent infection in the monkey model. Experimental allergic polyneuritis (EAN) in rhesus monkeys: Although cellular immune mechanisms are thought to be responsible for the development of EAN, the immunoregulatory mechanisms and participation of specific lymphocyte subsets in antigen recognition and demyelination during evolution of EAN are not known. We are serially recording lymphocytes during the development of EAN in rhesus monkeys using mouse monoclonal antibodies that recognize membrane markers of different lymphocyte subpopulations. Subacute sclerosing panencephalitis (SSPE): Young cynomolgus monkeys Macaca fasiculorus that were inoculated with "Biken" strain of measles virus (SSPE) have been monitored for clinical signs of disease. This is a long term project and signs of disease are not expected until 24-30 months post inoculation.